Depends on diet. Exercise burns calories - if you burn more calories than you consume, you lose weight, and cannot gain any muscle tissue - you can get stronger though, but due to neural adaptation. So long as you are in caloric deficit, you WILL lose weight. If you are not losing weight, you are not in caloric deficit. It is that simple, and cannot be argued with - it's simple physics. Whether that weightloss will be muscle tissue, fat or glycogen is anyone's guess, and depends on what kind of exercise you are doing, and what your diet is like. If you do the right kinds of exercises - i.e. train to provide an ample stimulus for muscle growth, and consume more calories than you burn, you might gain muscle - testosterone plays a role in building muscle, and as women have less testosterone than men, it's much harder for women to gain muscle.
Resistance exercise is the stimulus that encourages muscle growth - this can be in the form of weights, but also machines. Freeweights are better though, as it recruits more muscle fibres, and requires you to balance it and coordinate your movements. Things like yoga, pilates, cardio, etc will not build muscle in most people - they do not provide an intense enough stimulus to the muscles or nervous system.
If you're talking about bodyweight squats and lunges, they are very unlikely to build any muscle in the majority of people.